Male-specific epicuticular compounds of the sulfur butterfly Colias erate poliographus (Lepidoptera: Pieridae)

Abstract

Adults of the sulfur butterfly Colias erate poliographus Motschulsky showed sexual dimorphism in their epicuticular composition, with octadecanal and hexyl myristate, palmitate, and stearate identified as male-specific compounds in 3-day-old adults. Since males of the closely related North American species Colias philodice Godart also have the 3 hexyl esters and utilize them as aphrodisiac pheromones toward conspecific females, these substances are likely to serve as pheromones for C. erate. These male-specific compounds were more abundant in wings, especially forewings, than in the body. Male wings lacked androconia but possessed characteristic intermembranous cells. These cells were present behind the base of the socket of ordinary scales and distributed from the basal to discal areas in the forewing costal region and hind wing inner-marginal region. The intermembranous cells were morphologically similar to the male-specific secretory organs of C. philodice and seemed to be the source of the male-specific compounds of C. erate. However, in the wing areas including these cells, the wing scales contained larger amounts of male-specific compounds than the wing membrane, suggesting that the male-specific compounds produced in the intermembranous cells were transferred to and disseminated from the wing scales.